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Biomedical subjects

J E García

Publications and source records attributed to J E García.

18 recordsLinked to original sources
PubMed2003

[A scientific approach to the definition of quality in medical care: a model for Mexican reality].

This paper analyzes the problem of quality of medical care and its evolution in various health service institutions. It concludes that quality strategies for countries like Mexico should be of the decentralized/participant type, and that all quality programs in medical care should include five fundamental elements: evaluation, monitoring, design, development, and organizational change.

English Abstract↗
PubMed2003

Nonlinear characterization with burst excitation of 1-3 piezocomposite transducers.

Ultrasonic transducers made with 1-3 connectivity piezocomposites are frequently used in Medical applications and nondestructive testing. When the transducer is used for special applications as, for instance air-coupled transmission, it is necessary to compensate for the high difference of acoustic impedance between transducer and medium using high amplitude pulses to generate high acoustic signal. Thus, the nonlinear behavior of the transducer must be taken into account in similar application conditions. The newly developed method, which performs the nonlinear characterization with burst signal excitation near the thickness resonance frequency, is based on the measure of the current as well as the vibration velocity of the piezocomposite transducer. The current of the stationary response is measured before the end of the burst signal excitation. Burst excitation enables us to measure the nonlinear characterization without producing overheating in the transducers. The amplitude level dependence of mechanical losses tandelta(m) and the stiffness increases |Deltac/c(0)| have been studied, as well as the velocity dependence of a point of the transducer, measured with a laser vibrometer. In this method, the power level applied to the transducers can be higher than other nonlinear measurement methods, providing measurements of high accuracy.

Equipment Design↗
PubMed2001

Fertility options for female cancer patients: facts and fiction.

OBJECTIVE: To review the latest progress in the prevention of ovarian failure induced by chemo/radiotherapy, as well as the latest advances in culture technology and transplantation of frozen-thawed ovarian tissue. DESIGN: The English-language literature was searched with PubMed and related references. CONCLUSION(S): The development of combination chemotherapy and radiotherapy has improved the long-term survival of young cancer patients who are then frequently faced with iatrogenic ovarian failure and its consequences. The use of prior and concomitant GnRH analogs with chemotherapy offers encouraging results in animal studies with regard to prevention of ovarian failure. Adequately controlled research projects are needed to define the utility of GnRHa cotreatment in women cancer patients exposed to prolonged chemotherapy. Ovarian tissue cryopreservation is the optimal procedure for follicle banking. Theoretic options include returning the banked tissue back to the original pedicle so that pregnancy could be achieved naturally. Alternatively, the tissue can be grafted to a heterotopic site, either as an autograft (i.e., rectus abdominis muscle sheath) or as a xenograft (i.e., immunodeficient mice). Follicles could also be grown in vitro. Until reliable ovarian culture technology becomes available, autologous transplantation offers the best prospect of using frozen-thawed ovarian tissue. A primary concern, however, is the issue of microscopic metastatic disease to the ovary and the possibility of tumor reimplantation. Areas of research should focus on optimizing the freeze/thaw procedure for ovarian tissue, minimizing the ischemia-reperfusion injury after transplantation, and detecting minimal residual disease in ovarian tissue grafts.

Antineoplastic Agents↗
PubMed1999

Cyclosporin A decreases human macrophage interleukin-6 synthesis at post-transcriptional level.

In addition to its well-established effect on T cells, cyclosporin A (CsA) also inhibits inflammatory cytokine production by macrophages. However, little is known about the mechanism of action of CsA on macrophage cytokine production. We measured the effect of CsA on basal and phorbol-myristate-acetate (PMA)-stimulated production of interleukin-6 using the human monocyte cell line U937 differentiated with dimethylsulfoxide (DMSO). Interleukin-6 levels were measured in supernatant and cell lysates using specific enzyme-linked immunosorbent assays. We found that CsA decreases not only IL-6 release but also cytokine synthesis. The concentration of CsA used did not affect either cell viability or proliferation. Three possibilities may be advanced to explain the CsA-due decrease in IL-6 production by macrophages: (a) inhibition of the synthesis of an early common regulatory protein, (b) inhibition of cytokine gene transcription, or (c) modulation of post-transcriptional events. The first possibility was tested by measuring the effect of cycloheximide on the experimental system during the first 3 hours of culture. Although cycloheximide decreased total cytokine synthesis, the pattern of cytokine modulation by CsA persisted. These data suggest that CsA-mediated macrophage cytokine inhibition is not mediated by an early common regulatory protein. To further explore the inhibition mechanism, we measured IL-6 mRNA levels by Northern blot. IL-6 mRNA levels were unaffected by CsA both in resting and PMA-stimulated cells. We conclude that in human macrophages CsA diminishes IL-6 production at post-transcriptional level.

Cell Differentiation↗
PubMed1998

[Acute poisoning from pesticides: human and economic costs].

The use of pesticides has produced great agricultural benefits and, at the same time, serious public health problems that need to be solved. According to studies performed in the 1980s and 1990s, every year about half a million to one and a half million cases of acute pesticide poisoning are notified, together with 3,000 to 28,000 deaths. The purpose of this study was to draw attention to the incidence of acute pesticide poisoning and to the social and economic costs that are attributable to pesticides in different parts of the world. We present data on the economic importance of the pesticide industry and describe the situation of acute poisonings from exposure to pesticides and consumption of contaminated foods. Such data show that pesticide poisonings are more frequent in developing countries than in industrialized countries, even though developing countries consume less pesticides. We also estimate the economic costs of pesticide poisonings and examine certain other aspects of the situation, underscoring the need to reduce pesticide use.

Global Health↗
PubMed1997

Effect of human hydrosalpinx fluid on murine embryo development and implantation.

OBJECTIVE: To determine the effect of hydrosalpinx fluid-containing medium on murine embryo development and implantation. DESIGN: The development of one-, two-, and four-cell mouse embryos in medium containing 5%, 10%, and 20% of human hydrosalpinx fluid was observed. Implantation rates of mouse embryos transferred into the uterine horn with hydrosalpinx fluid-containing media were determined. SETTING: Private hospital-based fertility center and IVF program. MAIN OUTCOME MEASURE(S): Percentage of embryos continuing cell division and implantation rates after ET. RESULT(S): Hydrosalpinx fluid in culture medium affected embryo development in a dose-dependent fashion. The injection of hydrosalpinx fluid-containing medium into the uterine horn did not affect embryo implantation. CONCLUSION(S): Hydrosalpinx fluid negatively affects murine embryo development, but its presence in the uterine horn at ET did not affect implantation.

Animals↗
PubMed1996

Effect of incremental time experience on the results of in vitro fertilization with intracytoplasmic sperm injection (ICSI).

PURPOSE: Our objective was to determine the effect of experience on the results with intracytoplasmic sperm injection. METHODS: The quarterly outcome with both ICSI and traditional in vitro fertilization (IVF) in 1994 was analyzed in 475 patients under age 40 undergoing 595 oocyte retrievals. The data represent 307 patients undergoing 379 retrievals for IVF and 165 patients undergoing 216 retrievals for ICSI. RESULTS: Fertilization rates with ICSI improved significantly each quarter (52.96, 62.17, 70.17, and 74.87% in Q-I, Q-II, Q-III, and Q-IV, respectively), while the rate with IVF improved significantly between Q-I (69.9%) and Q-II (80.10%) and slightly but significantly between Q-II and Q-IV (82.88%). The implantation rate per embryo after ICSI improved significantly after Q-I (6.17%) compared to Q-II (10.70%) and Q-IV (12.14%). The pregnancy rate per transfer with ICSI increased steadily after Q-I (13.79, 21.88, 23.53, and 25.00% in Q-I through Q-IV), reaching statistical significance between Q-I and Q-III and between Q-I and Q-IV. CONCLUSIONS: Although acceptable results can be obtained with ICSI after a relatively short period of time, optimum results require substantial experience.

Embryo Transfer↗
PubMed1996

Deleterious effect of the presence of hydrosalpinx on implantation and pregnancy rates with in vitro fertilization.

OBJECTIVE: To determine the effect of the presence of a unilateral or bilateral hydrosalpinx on the outcome with IVF-ET. DESIGN: Retrospective analysis of clinical and laboratory data. SETTING: Hospital-based private IVF center. PATIENTS: Eight hundred forty-six patients with tubal disease younger than age 40 years undergoing 1,766 stimulation cycles. In 118 cycles, a hydrosalpinx was noted sonographically (group I) whereas, in 1,648 cycles, no such image was documented. MAIN OUTCOME MEASURES: Pregnancy and implantation rates. RESULTS: Group I displayed a significantly lower pregnancy rate per transfer than group II (16.84% versus 36.83%) and a lower implantation rate (3.92% versus 11.53%). CONCLUSION: The presence of hydrosalpinx adversely affects the outcome of IVF.

Adult↗
PubMed1992

Neurotoxic components in normal serum.

Serum neurotoxicity was studied by adding whole or fractionated serum (adult human, adult horse, or newborn calf) to neuron-rich cultures prepared from various regions of embryonic (Days 14-15) rat brain, including spinal cord, ventral mesencephalon, cerebellum, septum, and striatum. Effects of serum were also tested on several types of embryonic non-neuronal cells (skeletal muscle myotubes, cardiac muscle myocytes, and fibroblasts from skin and lung). Serum concentrations of 50% or more killed more than 95% of all neurons within 3 days. Serum concentrations as low as 10% also killed some neurons, especially those from cerebellum. Septal, cerebellar, and spinal cord neurons were more sensitive than striatal or mesencephalic neurons. All the tested non-neuronal cells survived much better than neurons at serum concentrations of 20% or more. Neurotoxicity was present in both fresh (human) and previously frozen (human and animal) sera, and affected both young (4 days in vitro) and older (42 days in vitro) cultures. Neurotoxicity was greatly diminished by heating the serum to 56 degrees C for 30 min. Experiments indicated that serum toxicity was not due to lipoprotein, complement, or tumor necrosis factor. All serum neurotoxicity was retained by an ultrafilter with a nominal molecular weight cutoff of 10 kDa. The profile of neurotoxicity following gel filtration at neutral pH was variable, with high toxicity most consistently observed in fractions with apparent molecular weights exceeding 100 kDa, and variable degrees of toxicity at lower molecular weights.

Animals↗
PubMed1992

Biguanide related lactic acidosis: incidence and risk factors.

The objective of this study was to evaluate in an open population the incidence and risk factors of biguanide related lactic acidosis. All patients currently treated in the Department of Diabetes and Lipid Metabolism of the Instituto Nacional de la Nutrición and their records were reviewed for the present use or history of administration of biguanides. The study was complemented with a revision of all admissions of diabetic patients to the emergency room during 1987-1990. In the outpatient study, 235 cases were included. No case of lactic acidosis was found. A high percentage of the biguanide treated patients had one or more lactic acidosis related risk factors. In the emergency study, 609 admissions of 273 patients were included. In 17 patients a metabolic non-ketotic acidosis was diagnosed. The frequency of non-ketotic acidosis for the different treatments was: 29.4 cases x 1000 emergency admissions for sulphonylurea treated group, 32 for sulphonylurea plus phenformin treated and 47.94 for type II insulin treated patients. All cases had severe precipitant diseases that can cause lactic acidosis with or without associated biguanide administration. No metformin related cases were found. The conclusions of this study are that biguanides in general and metformin in particular are not associated with a high risk of lactic acidosis. Severe systemic dysfunction associated with intercurrent diseases, frequently observed in diabetic patients, is the main determinant for the appearance of lactic acidosis.

Acidosis, Lactic↗